Novel Approaches to Studying Mammalian Hot Spots of Recombination 1. We will continue our analysis of the molecular nature of the recombination hot spot found in the human beta globin gene complex and initiate studies on the hot spot found in the mouse immune response region using our yeast meiosis system. The goal of these investigations is to define the molecular nature of recombination hot spots at the nucleic acid level. 2. Applying a novel technology we recently developed for enzymatically amplifying DNA sequences we aim to determine the restriction fragment length polymorphism genotype of single sperm cells (haplotype determination) at the DNA level. The analysis of thousands of individual sperm using this system will allow us to study the actual frequency of recombination between very closely linked RFLPs without family studies and can be used to directly study human recombination hot spots as well as to derive accurate genetic maps over very short distances.